Lord Justice Dingemans said: “Separate gatherings, separated both in time and by many miles, even if co-ordinated under the umbrella of one body, are not a public assembly within the meaning of… the Act.

“The XR [Extinction Rebellion] autumn uprising intended to be held from October 14 to 19 was not therefore a public assembly… therefore the decision to impose the condition was unlawful because there was no power to impose it under… the Act.”

The judges noted that there are powers within that act which may be used lawfully to “control future protests which are deliberately designed to ‘take police resources to breaking point”‘.

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Image caption Green Party peer Jenny Jones (centre) was among those to bring the successful legal challenge to court

During 10 days of climate change protests last month, activists shut down areas around Parliament and the Bank of England, and targeted London City Airport.

Police had previously warned protesters to keep demonstrations in Trafalgar Square, or risk arrest – before issuing a city-wide ban on 14 October, under Section 14 of the Public Order Act.

The court was told that the ban was issued on the same day as a message posted online by London activists.

It told protesters to adopt the “be water” tactics used by demonstrators in Hong Kong.

Analysis

BBC home affairs correspondent Daniel Sandford

This was a radical tactic adopted by the Metropolitan Police on 14 October – banning all future Extinction Rebellion protests across London for several days.

But it has backfired. No police force likes to have their actions described as “unlawful”.

Today’s High Court ruling takes away from officers the ability to impose a city-wide ban of future protests, which means demonstrators wanting to be “like water” – where they split into fast-moving groups – will be difficult to control if they are trying to disrupt a whole city.

So police will have to deal with what is in front of them.

If a specific protest in a specific place gets out of hand they will be able to close it down, but it will have to be a decision made by an officer on the spot, and not by someone sitting in a police station worrying about what protests may happen the next day.